WASHINGTON — Surrogates for President Barack Obama and Mitt Romney squared off Wednesday during a debate on energy policy that revealed stark differences between the two candidates' views of the federal government's role in using taxpayer dollars to support still-developing energy technologies.

Dan Reicher, a representative of the Obama campaign, argued that federal dollars can be used wisely to leverage private sector spending and to keep the U.S. competitive in a global race to commercialize new energy technologies.

“The government has an appropriate role to play,” said Reicher, a Stanford University professor who previously headed energy initiatives for Google.

Linda Stuntz, representing the Romney campaign, backed some government spending to propel research and development of energy technologies but said science and the free market should drive most investments, not White House whims.

“The U.S. should not be playing venture capitalist with taxpayer dollars,” said Stuntz, a former deputy secretary at the Energy Department under President George H.W. Bush.

Stuntz said Romney would end an expiring production tax credit that has helped pay for wind farms nationwide for more than two decades, but she was uncertain how quickly the program should be phased out. The tax credit is set to expire at the end of the year, unless Congress votes to renew it.

“We now have wind and solar industries dependent on subsidies,” Stuntz said. “When is enough? What is justified for American consumers to continue paying for a technology that either is cost-competitive ... or it's not and it can only exist because of taxpayer subsidies?”

Reicher accused Romney of being wedded to conventional oil and gas to the expense of alternative energy sources.

“There (are) a number of areas where Gov. Romney's bet is essentially on being able to drill our way out of this,” Reicher said. “I don't think the resources are there overall. I don't think it gives us the diversity of supply we need from a security perspective. And it cedes market internationally to what is a rapidly growing opportunity around clean energy technologies.”

On the campaign trail, Romney has pledged that if elected, he would immediately approve the controversial Keystone XL pipeline that would send oil sands crude from Alberta, Canada, to Gulf Coast refineries, a commitment Stuntz reiterated Wednesday.

Reicher said the Obama administration was moving toward making a decision on the proposed pipeline in the first quarter of 2013.

Both campaign representatives touted the potential for oil exploration in the Arctic Ocean, as Shell moves closer to launching exploratory drilling in the region once the ice clears this summer.